Beer Terminology Flashcards
Acetaldehyde
The most common of the aromatic chemical compounds called aldehydes. Produced in the early stages of fermentation and reduced to ethanol in the latter stages.Beer containing excessive levels of acetaldehyde is charactarized by the aroma and taste of green apple.
Beyond it’s presence as a background note it is generally considered an off flavor. If yeast is not sufficiently active, too much acetaldehyde may remain in the beer.
Alpha Acids
The principal components in lupulin, the resin of the hop cone. They are the primary bittering agents in hops. The alpha acid level of a given hop is expressed as a percentage of the hop’s weight (commonly in a range of 2%-18%).
Amarillo Hop
A proprietary, trademarked aroma hop introduced in 2000. Alpha acid range of 8%-11%, beta acid range 6%-7%, and a cohumulone range of 21%-24%.
The aroma profile is floral and citrus-like, with notes of tangerine and apricot. Similar in aroma to Cascade and, to some degree, the recent higher alpha Simcoe and Summit.
Commonly used in craft-brewed pale ales, IPAs, and double IPAs, where it is often employed as a dry hop.
Astringency
A drying, puckering taste; tannic; can be derived from boiling the grains, long mashes, over sparging or sparging with hard water. Often confused with bitterness. While some balanced astringency can be pleasant in certain beer styles, notable astringency is generally considered to be a flavor fault.
Attenuation
Involves the removal of sugars and production of alcohol by yeast during fermentation such that the wort becomes less dense and viscous and is thus thinned-out.
The extent of attenuation achieved in fermentation of wort to beer is often given as the difference between the starting gravity of the unfermented wort and the gravity of the finished beer, expressed as a percentage of the starting gravity.
Diacetyl
A flavor compound present in most beers, imparting aroma characteristics described as butter, butterscotch, or buttermilk when detected above its flavor threshold. Generated as a by-product of amino acid metabolism in yeast during fermentation.
Yeast excretes a precursor into the fermenting beer, where it breaks down chemically to produce diacetyl. However, the diacetyl is subsequently reabsorbed by the yeast cell and converted to a compound with no significant flavor characteristics. Yeasts that separate out too early in the fermentation process, often the result of early application of cooling, can fail to complete the reabsorption.
Diacetyl is particularly unwelcome in lager-style beers and these beers are often held time before cooling is applied, a process known as “warm condition” or “diacetyl rest.”
At low to moderate levels, diacetyl can be perceived as a positive in some ales and stouts. The amount is yeast strain dependent but wort composition and fermentation conditions are also significant contributors. Diacetyl can also me formed by certain beer spoilage bacteria (within the group known as lactic acid bacteria), most notably during the post-fermentation storage and sometimes in unsanitary beer lines (plastic tubing not cleaned properly).
Dimethyl Sulfide
An organic sulfur-containing molecule with an odor that is generally described as cooked sweet corn. Most brewers regard DMS as an off-flavor, but in moderation it does make a significant contribution to the aroma of many lager beers and has been identified as a key feature of German-style lagers.
4-vinyl guaiacol
An aromatic phenol that can be naturally found in most beers. Generally found in weissbiers, rauchbiers, and some specialty Belgian beers in notable concentrations, generally imparting desirable spicy, pungent, clove-like notes. At higher concentrations and under certain conditions it may present as a medicinal, off-flavor note.
